In recent years, the mechanism by which mammalian immune systems, such as human and murine systems react to infections, foreign antigens, and to so-called "self antigens" in connection with autoimmune diseases has begun to be established. See, in this regard, Grey, et al., Scientific American 261(5): 56-64 (1989); Male, et al., Advanced Immunology (J. P. Lippincott Company, 1987), especially chapters 6 through 10.
Well known, both to the skilled artisan and to the general public is the role of antibodies, sometimes referred to as "immunoglobulin" or the less correct and older "gammaglobulin" in response to infection. Antibodies are protein molecules which are produced by B cells in response to infection. It is well known that these antibodies act to "disable" or to inactivate infectious agents in the course of combating the infection.
In order for antibodies to be produced, however, preceding events must occur which lead to stimulation of the B cells which produce the antibodies. One of the key events involved in the processes leading to antibody production is that of antigen recognition. This aspect of the immune response requires the participation of so-called "T-cells", and is less well known than the antibody response commented on supra.
Briefly, and in outline form, antigen recognition requires interaction of an "antigen presentation cell", a "processed antigen", and a T-cell. See Grey and Male, supra. The "processed antigen", in an infection, is a molecule characteristic of the pathogen which has been treated, i.e., "processed", by other cells which are a part of the immune system. The processed antigen interacts with a receptor on the surface of an antigen presented in a manner not unlike a lock fitting into a key hole or, perhaps more aptly, two pieces of a jigsaw puzzle.
The configuration of the complex of processed antigen and receptor on antigen presentation cell allows the participation of T-cells. T-cells do not join the complex unless and until the processed antigen has fit into the receptor on the antigen presentation cell. This receptor will hereafter be referred to by its scientific name, the major histocompatibility complex (MHC), or the human leukocyte antigen (HLA). Generally, MHC is used to refer to murine systems, and HLA to humans.
These receptors fall into two classes. MHC-II molecules are involved in most responses to pathogens. In contrast, MHC-I molecules are involved when the pathogen is a virus, or a malignant cell is involved. When MHC-I participation is involved, there is no antibody stimulation; rather, the interaction of MHC-I, processed antigen and T-cell leads to lysis of cells infected with the pathogen.
The foregoing discussion has focused on the events involved in responding to "infection", i.e., the presence of pathogenic foreign material in the organism. Similar mechanisms are involved in autoimmune diseases as well. In these conditions, the organism treats its own molecules as foreign, or as "self-antigens". The same type of complexing occurs as described supra, with an antibody response being mounted against the organism itself. Among the diseases in which this is a factor are rheumatoid arthritis, diabetes, systemic lupus erythematosis, and others.
The ability of the T-cell to complex with the processed antigen and MHC/HLA complex is dependent on what is referred to as the T-cell antigen receptor, referred to as "TCR" hereafter. The TCR is recognized as a heterodimer, made up of alpha (.alpha.) and beta (.beta.) chains. Five variable elements, coded for by germline DNA and known as "V.alpha., J.alpha., V.beta., D.beta., and J.beta." as well as non-germline encoded amino acids contribute to the TCR. See, in this regard, Marrack, et al., Immunol. Today 9: 308-315 (1988); Toyonaga, et al., Ann. Rev. Immunol 5: 585-620 (1987); Davis, Ann. Rev. Immunol 4: 529-591 (1985); Hendrick, et al., Cell 30: 141-152 (1982). With respect to the binding of TCR with processed antigen and MHC, see Babbitt, et al., Nature 317: 359-361 (1985); Buus, et al., Science 235: 1353-1358 (1987); Townsend, et al., Cell 44: 959-968 (1986); Bjorkman, et al., Nature 329: 506-512 (1987).
Generally, both the alpha and beta subunits are involved in recognition of the ligand formed by processed antigen and MHC/HLA molecule. This is not always the case, however, and it has been found that so-called "superantigens" stimulate T-cells with a particular V.beta. element, regardless of any other element. See Kappler, et al., Cell 49: 273-280 (1987); Kappler, et al., Cell 49: 263-271 (1987); MacDonald, et al., Nature 332: 40-45 (1988); Pullen, et al., Nature 335: 796-801 (1988); Kappler, et al., Nature 332: 35-40 (1988); Abe, et al., J. Immunol 140: 4132-4138 (1988); White, et al., Cell 56: 27-35 (1989); Janeway, et al., Immunol. Rev. 107: 61-88 (1989); Berkoff, et al., J. Immunol 139: 3189-3194 (1988), and Kappler, et al., Science 244: 811-813 (1989). This last reference discloses information which is also incorporated into the subject patent application.
The "superantigens" mentioned supra, while generally stimulating T-cells as long as they possess a V.beta. element, are somewhat specific in terms of the particular form of the V.beta. moiety which is present on the stimulated T cell. This feature is one aspect of the invention, i.e., the ability to assay for particular subtypes or subclasses of T-cells, based upon the cell surface antigens presented by these subclasses.
Staphylococcus aureus has long been implicated in morbidity and mortality in humans. See Bergdoll, in Feed Bourne Infections and Intoxications (Riemann and Bryan, ed., Acad. Press, N.Y.) pp. 443-494 (1979). The various toxins presented by S. aureus are responsible for most food poisoning cases, as well as severe shock, and other life threatening pathological conditions. The mechanism of action of the toxins associated with S. aureus is unknown. The primary structure of the toxins, while showing some relationship, also show some great differences in primary structure. See Betley, et al., J. Bacteriol 170: 34-41 (1988); Jones, et al., J. Bacteriol 166: 29-33 (1986); Lee, et al., J. Bacteriol 170: 2954-2960 (1988); Blomster-Hautamaa, et al., J. Biol. Chem. 261: 15783-15786 (1986). For the time being, it cannot be said with any certainty whether the various S. aureus antigens function in the same way in terms of the immunological response they generate.
The ability of S. aureus to stimulate powerful T cell proliferative responses in the presence of mouse cells bearing MHC-II type molecules is taught by, e.g., Carlson, et al. J. Immunol 140-2848 (1988); White, et al., Cell 56 27-35 (1989); Janeway, et al., Immunol. Rev. 107:61-88 (1989). White, et al., and Janeway, et al. showed that one of these proteins is not mitogenic, in that it selectively stimulates murine cells which bear particular V.beta. elements. These papers, however, did not extend the study to human cells. It has now been shown, however, that certain antigens do selectively stimulate specific V.beta. subclasses of human T cells, making it possible to diagnose pathological conditions by assaying for particular V.beta. subtypes.
Hence, it is an object of the invention to describe a method for diagnosing a pathological condition in a human by assaying a biological sample from the subject being tested for levels of particular V.beta. subtypes. These levels are then compared to normal levels, where a difference between the two is indicative of a pathological condition.
It is a further object of the invention to carry out the assaying using antibodies which are specific for the particular V.beta. subtype. Especially preferred are monoclonal antibodies.
It is still another object of the invention to perform the above described assay by measuring DNA coding for specific V.beta. molecules. This can be done via utilizing, e.g., the polymerase chain reaction.
How these and other objects of the invention are achieved are detailed in the disclosure which follows.